DirtyBear0311 said:
Is it that the timing really is unchanged from season to season and if so, cant all of the areas simply be mapped?
Correct. In any given location, breeding will peak around the same date (give or take a couple of days) every year. And yes, this can be mapped. In fact, some state wildlife agencies publish breeding date maps for their individual state. As an example, here is one such map for the state of Mississippi:
http://www.mdwfp.com/wildlife-hunting/d ... e-map.aspx
Just remember that these average breeding dates are the average of all known conception dates for that location. However, don't think all breeding occurs on that exact date. Even in areas with a short and intense rut, 95% of conceptions are spread across 5 or 6 weeks. In areas with very strung out rut, 95% of conceptions may be strung out over several months.
When I or others discuss "peak breeding" we are often talking about the 10-14 day window within the breeding season when 50+% of does conceive. Even in areas with a tight rut that takes 5-6 weeks to complete, the conception dates are not equally spread across those weeks. Conceptions will form a very predictable pattern across this time frame, with the majority packed into a peak two week period (and sometimes as short as 10 days) towards the front end of the breeding season. As an example, below is a graph of real-world conception dates I helped compile for a research project. This local deer population had a very tightly timed rut, in that all known conceptions occurred over a 6 week period. Each data point displayed is the percent of conceptions that occurred during a 7 day period (see the dates along the bottom of the graph). Notice how conceptions peaked early in the process, with 65% of conceptions occurring during the 2nd (Nov. 15-21) and 3rd week (Nov. 22-28). In fact, more than 50% of conceptions occurred in a 10-day window within those peak two weeks, which I would refer to as the "peak of breeding" (If I remember correctly, that 10-day window was Nov. 17-26). This distribution of conception dates is quite classic for most localized deer populations,
although the actual dates will be different for each location. Some locations have peak breeding windows in late October, and some not until February.
So I know that the moon and other gravitational factors have nothing to do with it, but what exactly does influence the timing of the rut in particular areas?
Peak breeding is different in different locations primarily due to Natural Selection. In essence, whatever time of the year will produce the highest fawn survival drives when breeding will occur (approximately 200 days prior to peak fawn survival conditions). So what really drives breeding dates is what fawning dates will produce the highest fawn survival. Now sometimes the reasons why particular fawning dates produce the highest fawn survival is easy to deduce, but it many situations we really have no idea why one set of fawning dates is better in location A while a different set of fawning dates is better in location B (resulting in different peak breeding dates between the two locations).
Beyond Natural Selection, other factors can contribute to changes in breeding from year to year, although often these changes only occur slowly over a number of years. For example, poor herd dynamics, such as skewed adult sex ratios and poor buck age structure (most bucks are very young) have been shown to delay breeding. However, in TN, differences in herd dynamics can probably only delay breeding dates 7-10 days. In the Deep South, they have been shown to delay breeding by a month or more. In the North, breeding dates are so strongly genetically driven that differences in herd dynamics appears to play no role in breeding timing.
In addition, poor doe health can delay breeding (something I believe many in TN witnessed during the big EHD outbreak in 2007).
